PROJECT SUMMARY Concern has developed that marketing, not evidence, drives clinical practice. The use of expensive new medications often extends well beyond their established value. Recent independent, objective comparisons of oral antipsychotic preparations have provided little support for the market saturation achieved by the newer atypical antipsychotic medications. One long-acting injectable (LAI) atypical antipsychotic medication, risperidone microspheres (RM) is currently available at an average wholesale price that is approximately $8,000 per patient per year higher than generic conventional LAI preparations (e.g., fluphenazine decanoate-- FD). No study comparing RM and FD has been conducted that justifies this premium pricing. Two additional atypical LAI preparations (olanzapine pamoate and paliperidone palmitate) may become available within the coming year, and we can expect that aggressive marketing of these new drugs will increase the use of LAI antipsychotics considerably. The objective of the proposed research is to compare the effectiveness, costs, and tolerability of RM and restricted dose FD in patients with schizophrenia or schizo-affective disorder (SCH/SCHAFF). A core purpose of the Schizophrenia Trials Network (STN) is to provide, for clinicians and policy makers, independent, objective comparisons of medications used to treat patients with schizophrenia. Three hundred and sixty (360) patients with SCH/SCHAFF will be randomly assigned to up to 42 months of blinded treatment with either RM or restricted dose FD. The primary outcome measure for this trial will be time to relapse. Repeated assessments of service utilization, psychopathology, and adverse events will be made throughout the trial. Fasting samples for measurement of glucose, insulin, lipids, and prolactin will be obtained at regular intervals throughout the trial. The trial will utilize the NIMH STN infrastructure, including its Administrative and Implementation Units, and Data Management and Analysis Units. The trial will be conducted at 25 STN sites, representing a broad array of clinical settings to generate generalize-able and pragmatically relevant information. The STN will provide comprehensive oversight to ensure the successful implementation of the trial, including rapid start-up procedures and implementation, real-time monitoring for high quality data, and efficient data analysis and manuscript preparation.